Supplemental Guarantor Financial Information (Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss)) (Details) - USD ($) $ in Thousands		3 Months Ended
		Mar. 31, 2018	Mar. 31, 2017
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue		$ 1,396,834	$ 1,158,184
Costs of revenue, excluding depreciation and amortization		1,237,299	971,134
Depreciation and amortization		49,940	42,904
General and administrative expenses		63,622	64,781
Interest expense (income), net		17,058	12,597
Equity in earnings of unconsolidated affiliates		(5,585)	(1,646)
Other (income) expense, net		(3,089)	429
Income before income taxes		37,589	67,985
(Provision for) benefit from income taxes		(11,126)	(27,358)
Net income (loss) before equity in income from subsidiaries		26,500	40,600
Equity in income (losses) from subsidiaries, net of tax		0	0
Net income		26,463	40,627
Net loss attributable to non-controlling interests		(97)	(343)
Net income attributable to MasTec, Inc.	[1]	26,560	40,970
Comprehensive income (loss)		33,656	42,441
Reportable Legal Entities [Member] | MasTec, Inc. [Member]
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue		0	0
Costs of revenue, excluding depreciation and amortization		0	0
Depreciation and amortization		0	0
General and administrative expenses		800	600
Interest expense (income), net		0	0
Equity in earnings of unconsolidated affiliates		0	0
Other (income) expense, net		0	0
Income before income taxes		(800)	(600)
(Provision for) benefit from income taxes		200	200
Net income (loss) before equity in income from subsidiaries		(600)	(400)
Equity in income (losses) from subsidiaries, net of tax		27,100	41,400
Net income		26,500	41,000
Net loss attributable to non-controlling interests		0	0
Net income attributable to MasTec, Inc.		26,500	41,000
Comprehensive income (loss)		33,800	42,800
Reportable Legal Entities [Member] | Guarantor Subsidiaries [Member]
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue		1,265,600	1,083,200
Costs of revenue, excluding depreciation and amortization		1,136,200	888,700
Depreciation and amortization		43,300	35,300
General and administrative expenses		59,200	59,600
Interest expense (income), net		32,900	27,900
Equity in earnings of unconsolidated affiliates		0	0
Other (income) expense, net		(2,600)	0
Income before income taxes		(3,400)	71,700
(Provision for) benefit from income taxes		800	(26,300)
Net income (loss) before equity in income from subsidiaries		(2,600)	45,400
Equity in income (losses) from subsidiaries, net of tax		0	0
Net income		(2,600)	45,400
Net loss attributable to non-controlling interests		0	(100)
Net income attributable to MasTec, Inc.		(2,600)	45,500
Comprehensive income (loss)		(2,600)	45,500
Reportable Legal Entities [Member] | Non-Guarantor Subsidiaries [Member]
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue		185,600	87,900
Costs of revenue, excluding depreciation and amortization		155,500	95,300
Depreciation and amortization		6,600	7,600
General and administrative expenses		3,600	4,600
Interest expense (income), net		(15,800)	(15,300)
Equity in earnings of unconsolidated affiliates		(5,600)	(1,600)
Other (income) expense, net		(500)	400
Income before income taxes		41,800	(3,100)
(Provision for) benefit from income taxes		(12,100)	(1,300)
Net income (loss) before equity in income from subsidiaries		29,700	(4,400)
Equity in income (losses) from subsidiaries, net of tax		0	0
Net income		29,700	(4,400)
Net loss attributable to non-controlling interests		(100)	(200)
Net income attributable to MasTec, Inc.		29,800	(4,200)
Comprehensive income (loss)		36,800	(2,700)
Eliminations [Member]
Condensed Unaudited Consolidating Statements of Operations and Comprehensive Income (Loss) [Line Items]
Revenue		(54,400)	(12,900)
Costs of revenue, excluding depreciation and amortization		(54,400)	(12,900)
Depreciation and amortization		0	0
General and administrative expenses		0	0
Interest expense (income), net		0	0
Equity in earnings of unconsolidated affiliates		0	0
Other (income) expense, net		0	0
Income before income taxes		0	0
(Provision for) benefit from income taxes		0	0
Net income (loss) before equity in income from subsidiaries		0	0
Equity in income (losses) from subsidiaries, net of tax		(27,100)	(41,400)
Net income		(27,100)	(41,400)
Net loss attributable to non-controlling interests		0	0
Net income attributable to MasTec, Inc.		(27,100)	(41,400)
Comprehensive income (loss)		$ (34,300)	$ (43,200)

[1] Calculated as total net income less amounts attributable to non-controlling interests.